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71.
M. Alducin R. Díez Muio J.I. Juaristi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):431-437
The screening of a He+ ion embedded in a free electron gas is studied for different spin-polarizations of the medium. Density functional theory and the local spin density approximation are used to calculate the induced electronic density for each spin orientation, i.e. parallel or antiparallel to the spin of the electron bound to the ion. Since both the He+ ion and the electron gas are spin-polarized, we analyze in detail the spin state of the screening cloud for the two different possibilities: the spin of the bound electron can be parallel to either the mayority spin or the minority spin in the medium. Finally, the spin-dependent Kohn–Sham orbitals are used to calculate the Auger neutralization rate of the He+ ion. The polarization of the Auger excited electron is influenced by the spin-polarization of the medium. The results are discussed in terms of the spin-dependent screening and the indistinguishability of electrons with the same spin state. 相似文献
72.
César Muñoz Víctor Carreño Gilles Dowek Ricky Butler 《International Journal on Software Tools for Technology Transfer (STTT)》2003,4(3):371-380
Safety assessment of new air traffic management systems is a main issue for civil aviation authorities. Standard techniques
such as testing and simulation have serious limitations in new systems that are significantly more autonomous than the older
ones. In this paper, we present an innovative approach for establishing the correctness of conflict detection systems. Fundamental
to our approach is the concept of trajectory, and how we represent a continuous physical trajectory by a continuous path in
the x-y plane constrained by physical laws and operational requirements. From the model of trajectories, we extract, and formally
prove, high-level properties that can serve as a framework to analyze conflict scenarios. We use the AILS (Airborne Information
for Lateral Spacing) alerting algorithm as a case study of our approach.
Published online: 19 November 2002 相似文献
73.
74.
A new thermal tracing technique is presented for the measurement of enthalpy interchange between connected subchannels in one-phase axial flow. The method is simple and versatile, being capable of implementation on compact and non-homogeneous bundles using water as fluid. To present the technique, measurements of turbulent mixing were performed on a triangular array bundle with a relation of pitch to diameter of 1.33, at Reynolds numbers between 104 and 6.8×104. For this simple arrangement the precision of the method is discussed showing that accuracies better than 10% can be readily achieved. Measurements are also performed in presence of a mixing vane showing another field were the method can be advantageously applied. 相似文献
75.
New stainless steel inserts are developed for fastening sheet molding compound (SMC). Using these molded-in inserts, SMC components can be assembled without protrusions. The inserts consist of two mating surfaces which interlock through the existence of a shoulder male boss and a shoulder female counterbore. Repeated assembly and disassembly can take place without damaging the material being fastened. The strength of the joint, when using these interlocking inserts, is comparable to that when using bolts. Also being investigated is the strength of the joint after being immersed in water for half a month. The difference between the dry and wet strengths for the inserted samples is less than that for the bolted samples. Load versus extension plots show that these particular inserts provide a more rigid joint than a bolted connection. 相似文献
76.
Veronica Conti Claudio Cantini Marco Romi Maria Michela Cesare Luigi Parrotta Stefano Del Duca Giampiero Cai 《International journal of molecular sciences》2022,23(10)
Future climate scenarios suggest that crop plants will experience environmental changes capable of affecting their productivity. Among the most harmful environmental stresses is drought, defined as a total or partial lack of water availability. It is essential to study and understand both the damage caused by drought on crop plants and the mechanisms implemented to tolerate the stress. In this study, we focused on four cultivars of tomato, an economically important crop in the Mediterranean basin. We investigated the biochemical mechanisms of plant defense against drought by focusing on proteins specifically involved in this stress, such as osmotin, dehydrin, and aquaporin, and on proteins involved in the general stress response, such as HSP70 and cyclophilins. Since sugars are also known to act as osmoprotectants in plant cells, proteins involved in sugar metabolism (such as RuBisCO and sucrose synthase) were also analyzed. The results show crucial differences in biochemical behavior among the selected cultivars and highlight that the most tolerant tomato cultivars adopt quite specific biochemical strategies such as different accumulations of aquaporins and osmotins. The data set also suggests that RuBisCO isoforms and aquaporins can be used as markers of tolerance/susceptibility to drought stress and be used to select tomato cultivars within breeding programs. 相似文献
77.
Anca-Maria Istrate-Ofieru Elena-Iuliana-Anamaria Berbecaru George-Lucian Zoril Gabriela-Camelia Rou Laureniu Mihai Dîr Cristina Maria Comnescu Roxana Cristina Drguin Dan Ruican Rodica Daniela Nagy Dominic Gabriel Iliescu Laureniu Mogoant Daniel Pirici 《International journal of molecular sciences》2022,23(10)
Ectopic endometrial epithelium associates a wide spectrum of symptomatology. Their evolution can be influenced by inflammatory and vascular changes, that affect not only the structure and cell proliferation rate, but also symptoms. This prospective study involved tissue samples from surgically treated patients, stained using classical histotechniques and immunohistochemistry. We assessed ectopic endometrial glands (CK7+, CK20−), adjacent blood vessels (CD34+), estrogen/progesterone hormone receptors (ER+, PR+), inflammatory cells (CD3+, CD20+, CD68+, Tryptase+), rate of inflammatory cells (Ki67+) and oncoproteins (BCL2+, PTEN+, p53+) involved in the development of endometriosis/adenomyosis. A CK7+/CK20− expression profile was present in the ectopic epithelium and differentiated it from digestive metastases. ER+/PR+ were present in all cases analyzed. We found an increased vascularity (CD34+) in the areas with abdominal endometriosis and CD3+−:T-lymphocytes, CD20+−:B-lymphocytes, CD68+:macrophages, and Tryptase+: mastocytes were abundant, especially in cases with adenomyosis as a marker of proinflammatory microenvironment. In addition, we found a significantly higher division index-(Ki67+) in the areas with adenomyosis, and inactivation of tumor suppressor genes-p53+ in areas with neoplastic changes. The inflammatory/vascular/hormonal mechanisms trigger endometriosis progression and neoplastic changes increasing local pain. Furthermore, they may represent future therapeutic targets. Simultaneous-multiple immunohistochemical labelling represents a valuable technique for rapidly detecting cellular features that facilitate comparative analysis of the studied predictors. 相似文献
78.
Sara Oliveira Tamaeh Monteiro-Alfredo Rita Henriques Carlos Fontes Ribeiro Raquel Seia Teresa Cruz Clia Cabral Rosa Fernandes Ftima Piedade Maria Paula Robalo Paulo Matafome Snia Silva 《International journal of molecular sciences》2022,23(10)
Curcumin has been suggested as a promising treatment for metabolic diseases, but the high doses required limit its therapeutic use. In this study, a new curcuminoid is synthesised to increase curcumin anti-inflammatory and antioxidant potential and to achieve hypoglycaemic and protective vascular effects in type 2 diabetic rats in a lower dose. In vitro, the anti-inflammatory effect was determined through the Griess reaction, and the antioxidant activity through ABTS and TBARS assays. In vivo, Goto-Kakizaki rats were treated for 2 weeks with the equimolar dose of curcumin (40 mg/kg/day) or curcuminoid (52.4 mg/kg/day). Fasting glycaemia, insulin tolerance, plasma insulin, insulin signalling, serum FFA, endothelial function and several markers of oxidative stress were evaluated. Both compounds presented a significant anti-inflammatory effect. Moreover, the curcuminoid had a marked hypoglycaemic effect, accompanied by higher GLUT4 levels in adipose tissue. Both compounds increased NO-dependent vasorelaxation, but only the curcuminoid exacerbated the response to ascorbic acid, consistent with a higher decrease in vascular oxidative and nitrosative stress. SOD1 and GLO1 levels were increased in EAT and heart, respectively. Altogether, these data suggest that the curcuminoid developed here has more pronounced effects than curcumin in low doses, improving the oxidative stress, endothelial function and glycaemic profile in type 2 diabetes. 相似文献
79.
Augusta de Santis Ernesto Scoppola Maria Francesca Ottaviani Alexandros Koutsioubas Lester C. Barnsley Luigi Paduano Gerardino DErrico Irene Russo Krauss 《International journal of molecular sciences》2022,23(10)
Lipid structural diversity strongly affects biomembrane chemico-physical and structural properties in addition to membrane-associated events. At high concentrations, cholesterol increases membrane order and rigidity, while polyunsaturated lipids are reported to increase disorder and flexibility. How these different tendencies balance in composite bilayers is still controversial. In this study, electron paramagnetic resonance spectroscopy, small angle neutron scattering, and neutron reflectivity were used to investigate the structural properties of cholesterol-containing lipid bilayers in the fluid state with increasing amounts of polyunsaturated omega-3 lipids. Either the hybrid 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine or the symmetric 1,2-docosahexaenoyl-sn-glycero-3-phosphocholine were added to the mixture of the naturally abundant 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and cholesterol. Our results indicate that the hybrid and the symmetric omega-3 phospholipids affect the microscopic organization of lipid bilayers differently. Cholesterol does not segregate from polyunsaturated phospholipids and, through interactions with them, is able to suppress the formation of non-lamellar structures induced by the symmetric polyunsaturated lipid. However, this order/disorder balance leads to a bilayer whose structural organization cannot be ascribed to either a liquid ordered or to a canonical liquid disordered phase, in that it displays a very loose packing of the intermediate segments of lipid chains. 相似文献
80.
Andrea Bagn Jos A. Morales-García Christian Grin-Ferr Caridad Díaz Jos Prez del Palacio Maria C. Ramos Francisca Vicente Beln Prez Jos Brea María Isabel Loza Merc Palls Carmen Escolano 《International journal of molecular sciences》2022,23(10)
The impact of neurodegenerative diseases (ND) is becoming unbearable for humankind due to their vast prevalence and the lack of efficacious treatments. In this scenario, we focused on imidazoline I2 receptors (I2-IR) that are widely distributed in the brain and are altered in patients with brain disorders. We took the challenge of modulating I2-IR by developing structurally new molecules, in particular, a family of bicyclic α-iminophosphonates, endowed with high affinity and selectivity to these receptors. Treatment of two murine models, one for age-related cognitive decline and the other for Alzheimer’s disease (AD), with representative compound B06 ameliorated their cognitive impairment and improved their behavioural condition. Furthermore, B06 revealed beneficial in vitro ADME-Tox properties. The pharmacokinetics (PK) and metabolic profile are reported to de-risk B06 for progressing in the preclinical development. To further characterize the pharmacological properties of B06, we assessed its neuroprotective properties and beneficial effect in an in vitro model of Parkinson’s disease (PD). B06 rescued the human dopaminergic cell line SH-SY5Y from death after treatment with 6-hydroxydopamine (6-OHDA) and showed a crucial anti-inflammatory effect in a cellular model of neuroinflammation. This research reveals B06 as a putative candidate for advancing in the difficult path of drug discovery and supports the modulation of I2-IR as a fresh approach for the therapy of ND. 相似文献